Fig. 1. Potential peripheral interventions to prevent or rescue aging-associated cognitive decline.

A greater understanding of the impacts of circulating factors on the hippocampus may inform strategies to replace youthful factors lost during aging (a) or neutralize pro-aging factors (b). Alternatively, it may be more effective to deliver young or rejuvenated HSCs (c) or differentiated hematopoietic cells (d), or to target the bone marrow niche to rejuvenate endogenous HSCs (e).